In electronics, an audible audio signal is generated by generating an electrical signal representative of the audible signal and feeding that signal to a speaker. Various adjustments can be applied to the audio signal, including changing its volume, pitch and frequency, using known analog and digital signal processing techniques.
For a communication device, such as a cellular phone, a current feature provides a volume setting which selectively increases and decreases volume of an audio signal generated by the device's speaker. For a user of a cellular phone who has hearing difficulties, when he talks on the phone, the phone's volume setting may be placed at a “high” volume level, to increase the audio signal of the person calling the user. Alternatively, the volume setting may be set at a sufficiently high level to enable the user to listen to the audio signal generated by the cellular phone without requiring that the cellular phone be placed immediately near the user's ear. This setting is useful when the user checks his voice mail system. Therein, with a high volume level, he can hold the cellular phone in front of him and listen to his messages while still being able to see the keypad of the cellular phone. This enables him to see the keypad and quickly access the appropriate keys as he navigates through the commands of the voice mail system.
Increasing the volume on a cellular phone past a threshold level introduces distortion to the generated audio signal, thereby making it difficult to understand.
Known signal processing techniques provide dynamic monitoring of audio signals to dynamically recognize when an audio signal has excessive distortion and then provide a corrective shaping signal to it to reduce the distortion. Such techniques work very well, but use sophisticated evaluation techniques which require a significant amount of signal processing capabilities to implement them in real time. Smaller devices, such as cellular phones, have limited signal processing capabilities, and may not have sufficient capabilities to implement these techniques.
There is a need for a system and method of adjusting an audio signal in an efficient manner.